Microfluidic devices and systems have recently been developed for performing large numbers of different analytical and/or synthetic operations within the confines of very small channels and chambers that are disposed within small scale integrated microfluidic devices. These systems have proven extremely effective for performing a wide range of desired analytical operations at extremely high throughput rates, with much lower reagent requirements, and in a readily automatable format.
Despite the improvements in throughput and accuracy of individual microfluidic systems, as with any operation, multiplexing the basic system can substantially increase throughput, so that the operations of the system are carried out in highly parallelized systems. Specifically, by coupling together large numbers of individual systems, one can multiply the throughput of the system by the number of parallel systems.
Microfluidic devices and systems, because of their extremely small space requirements are particularly well suited for parallelization or multiplexing because large numbers of parallel analytical fluidic elements can be combined within a single integrated device that occupies a relatively small area, e.g., from about 1 cm.sup.2 to about 50 cm.sup.2. An example of such a parallelized or multiplexed device is described in, e.g., Published International Application No. 98/00231, which describes a microfluidic device, system and method for performing high throughput screening assays.
Because microfluidic systems can have complicated manufacturing processes, production yields of perfectly functioning devices can be relatively low. In the case of highly parallelized, multiplexed systems, the yield problems can be multiplied by the number of multiplexed or parallel systems. Merely by way of illustration, one might have a process of fabricating a channel network in a typical, single operation microfluidic device, where one of ten attempts at fabricating a functional channel network fails. Assuming that this probability of failure is the same for each separate channel network in a multiplexed system, e.g., including ten separate channel networks, one can see that the probability of producing a perfectly functioning multiplexed system is substantially reduced. This probability is further decreased as the number of multiplexed elements is increased.
Accordingly, it would generally be desirable to provide multiplexed microfluidic devices that have structures that permit higher fabrication yields, as well as methods of fabricating such devices. The present invention meets these and other needs.